Molecular oxygen reacts spontaneously in neutral solutions with certain metal-peptide complexes to oxidize the peptides. Copper and nickel catalyze this activation of O2, but the copper reaction is subject to photochemical inhibition. Trivalent copper and trivalent nickel are formed in the O2 reactions and act as catalysts. The mechanism of this catalytic behavior will be investigated. The Cu(III) peptide complexes will be generated by electrolysis and studied in regard to: (1) their oxidizing strength in acid, (2) the kinetics of their self decomposition from pH 0-14, (3) their photochemical decomposition, (4) the mechanism of reaction with O2. The redox properties of bispeptide complexes of Ni(III) will be studied. The overall objectives are to determine the scope, extent, specificity, mechanisms, and biological significance of the metal-catalyzed autoxidations and the nature and properties of the Cu(III) and Ni(III) complexes. BIBLIOGRAPHIC REFERENCES: "Ligand Effects on the Thermodynamic Stabilization of Copper(III)-Peptide Complexes," F. P. Bossu, K. L. Chellappa, and D. W. Margerum, J. Am. Chem. Soc., 99, 2195 (1977). "Electrode Potentials of Nickel(III,II)-Peptide Complexes," F. P. Bossu and D. W. Margerum, Inorg. Chem., 16, 1210 (1977).